Abstract

We study transient spatiotemporal structures induced by a weak space-time localized stimulus in an excitable contractile fiber within a two-component globally coupled reaction-diffusion model. The model which we develop allows us to analyze various regimes of excitation spreading and determine origin of the induced structures for various contraction types (defined by the fiber fixation) and global coupling strengths. One of the most notable effects we observed is the after-excitation effect. It leads to emergence of multiple excitation pulses excited by a single external stimulus and can result in long-lasting transient activity and appearance of new oscillatory attractor regimes, including the ones with multiple phase clusters.

Lead Paragraph: The reaction-diffusion-mechanics models are used to describe self-consistent electromechanical activity in a cardiac muscle. Such models couple two mechanisms of signal spreading in the tissue: the slow (reaction-diffusion) spreading of electrical excitation and the fast (almost instantaneous) spreading of mechanical deformations. Such coupling may significantly modify the electrical excitation spreading and corresponding contractile activity with emergence of new spatiotemporal structures and patterns. This effect is not yet completely understood even in the one-dimensional case of a single muscle fiber. We propose clear convenient model which allows study of electromechanical activity of such a fiber in relation to the mechanical parameters of the fiber fixation (such as stiffness of the tissue fixation and the applied mechanical load, which can be easily controlled in experiments). Using this model, we determine and analyze the physical origin of the primary dynamical effects, which can be caused in a cardiactissue by electromechanical coupling and mechanoelectrical feedback.

Acknowledgments:

This work was supported by the Russian Science Foundation (Section II, Grant No. 14-12-00811), the Ministry of Education and Science of the Russian Federation (Section III, Agreement No. 02.B.49.21.0003), the Russian Foundation for Basic Research (Section III, Grant No. 16-32-60166), and the Government of the Russian Federation (Section IV, Agreement No. 14.B25.31.0008).